S

Sedative-hypnotics

Uses

Treatment of insomnia (i.e., difficulty falling asleep initially, frequent awakening, awakening too early).

Action

Benzodiazepines are the most widely used agents and largely replace barbiturates due to greater safety, lower incidence of drug dependence. Benzodiazepines nonselectively bind to at least three receptor subtypes accounting for sedative, anxiolytic, relaxant, and anticonvulsant properties. Benzodiazepines enhance the effect of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), which inhibits impulse transmission in the CNS reticular formation in brain. Benzodiazepines decrease sleep latency, number of nocturnal awakenings, and time spent in awake stage of sleep; increase total sleep time. The nonbenzodiazepines zaleplon and zolpidem preferentially bind with one receptor subtype, reducing sleep latency and nocturnal awakenings and increasing total sleep time. Ramelteon is a selective agonist of melatonin receptors (responsible for determining circadian rhythms and synchronizing sleep-wake cycles).

Sedative-hypnotics

Name	Availability	Dosage Range	Side Effects
Benzodiazepines
Estazolam (ProSom)	T: 1 mg, 2 mg	A: 1–2 mg E: 0.5–1 mg	Daytime sedation, memory and psychomotor impairment, tolerance, withdrawal reactions, rebound insomnia, dependence
Flurazepam (p. 508) (Dalmane)	C: 15 mg, 30 mg	A/E: 15–30 mg	Headaches, unpleasant taste, dry mouth, dizziness, anxiety, nausea
Quazepam (Doral)	T: 15 mg	A: 7.5–15 mg E: 7.5 mg	Same as flurazepam
Temazepam (p. 1158) (Restoril)	C: 7.5 mg, 15 mg, 30 mg	A: 15–30 mg E: 7.5–15 mg	Same as flurazepam
Nonbenzodiazepines
Eszopiclone (p. 453) (Lunesta)	T: 1 mg, 2 mg, 3 mg	A: 2–3 mg E: 1–2 mg	Headaches, unpleasant taste, dry mouth, dizziness, anxiety, nausea
Ramelteon (p. 1033) (Rozerem)	T: 8 mg	A, E: 8 mg	Headaches, dizziness, fatigue, nausea
Zaleplon (p. 1292) (Sonata)	C: 5 mg, 10 mg	A: 5–20 mg E: 5 mg	Headaches, dizziness, myalgia, drowsiness, asthenia (loss of strength, energy), abdominal pain
Zolpidem (p. 1301) (Ambien, Ambien CR, Edluar, Zolpimist)	T: 5 mg, 10 mg CR: 6.25 mg, 12.5 mg SL: 5 mg, 10 mg OS: 5 mg/actuation	OS, T, SL: 5 mg (females); 5–10 mg (males) CR: 6.25 mg (females); 6.25–12.5 mg (males)	Dizziness, daytime drowsiness, headaches, confusion, depression, hangover, asthenia (loss of strength, energy)

A, Adults; C, capsules; CR, controlled-release; E, elderly; OS, oral solution; SL, sublingual; T, tablets.

Skeletal muscle relaxants

Uses

Central acting muscle relaxants: Adjunct to rest, physical therapy for relief of discomfort associated with acute, painful musculoskeletal disorders (i.e., local spasms from muscle injury).

Baclofen, dantrolene, diazepam: Treatment of spasticity characterized by heightened muscle tone, spasm, loss of dexterity caused by multiple sclerosis, cerebral palsy, spinal cord lesions, CVA.

Action

Central acting muscle relaxants: Exact mechanism unknown. May act in CNS at various levels to depress polysynaptic reflexes; sedative effect may be responsible for relaxation of muscle spasm.

Baclofen, diazepam: May mimic actions of gamma-aminobutyric acid on spinal neurons; does not directly affect skeletal muscles.

Dantrolene: Acts directly on skeletal muscle, relieving spasticity.

Skeletal muscle relaxants

Name	Indication	Dosage Range	Side Effects/Comments
Baclofen (p. 116) (Lioresal)	Spasticity associated with multiple sclerosis, spinal cord injury	Initially 5 mg 3 times/day Increase by 5 mg 3 times/day q3days Maximum: 20 mg 4 times/day	Drowsiness, dizziness, GI effects Caution with renal impairment, seizure disorders Withdrawal syndrome (e.g., hallucinations, psychosis, seizures)
Carisoprodol (p. 197) (Rela)	Discomfort due to acute, painful, musculoskeletal conditions	250–350 mg 4 times/day	Drowsiness, dizziness, GI effects Hypomania at higher than recommended doses Withdrawal syndrome Hypersensitivity reaction (skin reaction, bronchospasm, weakness, burning eyes, fever) or idiosyncratic reaction (weakness, visual or motor disturbances, confusion) usually occurring within first 4 doses
Chlorzoxazone (Lorzone)	Discomfort due to acute, painful, musculoskeletal conditions	Initially 250–500 mg 3–4 times/day Maximum: 750 mg 3–4 times/day	Drowsiness, dizziness, GI effects, rare hepatotoxicity Hypersensitivity reaction (urticaria, itching) Urine discoloration to orange, red, or purple
Cyclobenzaprine (p. 295) (Flexeril)	Muscle spasm, pain, tenderness, restricted movement due to acute, painful, musculoskeletal conditions	Initially 5–10 mg 3 times/day	Drowsiness, dizziness, GI effects Anticholinergic effects (dry mouth, urinary retention) Quinidine-like effects on heart (QT prolongation) Long half-life
Dantrolene (p. 312) (Dantrium)	Spasticity associated with multiple sclerosis, cerebral palsy, spinal cord injury	Initially 25 mg/day for 1 week, then 25 mg 3 times/day for 1 week, then 50 mg 3 times/day for 1 week, then 100 mg 3 times/day Maximum: 100 mg 4 times/day	Drowsiness, dizziness, GI effects Contraindicated with hepatic disease Dose-dependent hepatotoxicity Diarrhea that is dose dependent and may be severe, requiring discontinuation
Diazepam (p. 352) (Valium)	Spasticity associated with cerebral palsy, spinal cord injury; reflex spasm due to muscle, joint trauma or inflammation	2–10 mg 3–4 times/day	Drowsiness, dizziness, GI effects Abuse potential
Metaxalone (p. 757) (Skelaxin)	Discomfort due to acute, painful, musculoskeletal conditions	800 mg 3–4 times/day	Drowsiness (low risk), dizziness, GI effects Paradoxical muscle cramps Mild withdrawal syndrome Contraindicated in serious hepatic or renal disease
Methocarbamol (p. 762) (Robaxin)	Discomfort due to acute, painful, musculoskeletal conditions	Initially 1,500 mg 4 times/day Maintenance: 1,000 mg 4 times/day	Drowsiness, dizziness, GI effects Urine discoloration to brown, brown-black, or green
Orphenadrine (Norflex)	Discomfort due to acute, painful, musculoskeletal conditions	100 mg 2 times/day	Drowsiness, dizziness, GI effects Long half-life Anticholinergic effects (dry mouth, urinary retention) Rare aplastic anemia Some products may contain sulfites
Tizanidine (p. 1199) (Zanaflex)	Spasticity	Initially 4 mg q6–8h (Maximum 3 times/day), may increase by 2–4 mg as needed/tolerated Maximum: 36 mg (limited information on doses greater than 24 mg)	Drowsiness, dizziness, GI effects Hypotension (20% decrease in B/P) Hepatotoxicity (usually reversible) Withdrawal syndrome (hypertension, tachycardia, hypertonia) Effect is short lived (3–6 hrs) Dose cautiously with creatinine clearance less than 25 ml/min

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